Research Training in Pulmonary Immunology and Allergy at MGH is a T32 renewal application that brings together research programs of the Massachusetts General Hospital (MGH) Division of Pulmonary and Critical Care Medicine (DPCCM), Allergy and Clinical Immunology Unit (ACIU), and Center for Immunology and Inflammatory Diseases (CIID). This Training Program was created principally to provide comprehensive training for physician-scientists in the DPCCM and ACIU fellowship programs interested in lung immunology and allergic inflammation. The Program is designed to prepare the next generations of physician-scientists and PhD-scientists to be leaders in lung immunology and allergy related research. In the first 3.5 years, this Program has been highly successful with no unfilled slots and 100% academic retention. In addition, all of the graduates of the Program have published at least one first-author publication and 73% have secured independent funding. In this renewal application we capitalize on this success and momentum and provide training in 10 scientific disciplines: (i) Adaptive Lung Immunity; (ii) Innate Lung Immunity; (iii) Allergic Sensitization, Tolerance & Immunodeficiency; (iv) Lung Injury, Repair & Regeneration; (v) Molecular Epidemiology & Genetics of Lung Disease and Allergy; (vi) Health Care Delivery Science in Pulmonary and Allergy; (vii) Translational & Precision Medicine; (viii) Systems Biology, Single Cell Genomics & Epigenetics; (ix) Microbiome; (x) Novel Imaging Modalities. The Program will have basic, translational, health outcomes and epidemiology components. Specifically we seek to provide: 1) opportunities for mentored research in disciplines that have the potential for high-impact discoveries; 2) outstanding research training through didactics, seminars, and comprehensive mentoring; and 3) an environment and infrastructure that fosters scholarly activity and career development into independent scientists. This application requests 10 training positions that will be allocated to trainees who are committed to 2 to 3 years of research training. Eight MD or MD/PhD candidates will be drawn from the highly competitive DPCCM and ACIU fellowship programs. Two PhD trainees will be chosen from postdoctoral fellows in the laboratories of our mentors who are performing at a high level and who have demonstrated a commitment to careers in pulmonary or allergy research. Two new slots for PhD trainees are being requested based on trainee and mentor feedback indicating that our Program would be strengthened, and the mission of the NIH better served, by having MDs and PhDs train side-by-side. The 28 mentors in this Program were carefully chosen based on their track record of publications, grants, mentoring, collaboration and interest in lung immunology and allergy. MGH provides an outstanding training environment with over 1400 investigators, numerous training grants, research centers, trainee support groups, and over $850 million in research grant awards. Furthermore, opportunities at Harvard Medical School, the Harvard School of Public Health, and the Broad Institute provide additional valuable resources for trainees.